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U.S. Department of Energy
Office of Scientific and Technical Information

Air-fuel ratio control system

Patent ·
OSTI ID:6619351
This patent describes an air-fuel ratio control system for an internal combustion engine having an induction passage, means for supplying air-fuel mixture to the engine, an electromagnetic valve for correcting the air-fuel ratio of the air-fuel mixture supplied by the supplying means, an O/sub 2/ sensor for detecting oxygen concentration in exhaust gases of the engine, and a feedback control circuit. The control circuit comprises a comparator means for comparing the output of the O/sub 2/ sensor with a reference value for producing an output signal responsive to the comparison, means for generating basic pulses having a constant duty ratio, and calculating means responsive to the output signal of the comparator means for correcting the basic pulses such that a duty ratio thereof is dependent on the output signal. The corrected pulses are for driving the electromagnetic valve to correct the air-fuel ratio. A vacuum sensor is also included for sensing the pressure in the induction passage. The improvement described here comprises: pulse generating means for storing pulse trains which have different duty ratios dependent on the pressure in the induction passage and engine speed; vacuum detecting means for producing a first signal upon acceleration of the engine; and coolant temperature detecting means for producing a second signal at cold engine operation.
Assignee:
Fuji Jukogyo Kabushiki Kaisha, Tokyo
Patent Number(s):
US 4651699
OSTI ID:
6619351
Country of Publication:
United States
Language:
English